//
// Created by Semir on 2020/5/9.
//

#include <iostream>

using namespace std;

int rectCover(int number) {
    if (number < 3) {
        return number;
    }
    int i = 1;
    int j = 2;
    int res = 0;
    int cnt = number - 2;
    while (cnt) {
        res = i + j;
        i = j;
        j = res;
        cnt--;
    }
    return res;
}

int main() {
    int res = rectCover(1);
    cout << res << endl;
    return 0;
}